1. Field of the Invention
The present invention relates to an apparatus for a continuous mixing of particulate solid material with a liquid, and more particularly, but not by way of limitation, to a continuous cement mixing apparatus.
In oil and gas well applications it is often necessary to provide cement mixers which will rapidly prepare large quantities of material to be pumped into the well by a continuous process until a sufficient predetermined quantity has been applied. A paddle or rotary type mixer while being able to adequately perform the mixing operation requires a large volume and since the mixing must be done on site the bulk and weight of the equipment used is prohibitively expensive. Continuous monitoring of all such rotary mixing equipment must be made in order to insure that the slurry does not become so thick as to cause the paddles or rotary device to stick. The cleanup operation of the equipment after use can also be a severe problem in the field.
Jet type mixers function well in making ordinary cement slurries but the adequate mixing of gel cements has proven difficult with the jet type mixer. Also, the jet mixer usually requires the use of one of the treating pumps in order to drive the jet, thereby reducing the treating capacity.
In recent years vortex mixers of the type disclosed and claimed in U.S. Pat. Nos. 3,201,093 and 3,741,533 have been used with considerable success. However, the device of the first mentioned patent has an inherent problem in mixing dense slurries while the second mentioned patent having somewhat overcome the problem, has required the use of excessive horsepower in mixing the dry bulk with the liquid.